NVIDIA GPU users! Help me out!

Ok, so today I received my additional NVIDIA 660 2GB Graphics Card. I've used a single one for a little over a year now, and now that theyre $120 for a new one I figured i'd buy a second one and SLI them. Because why not.

So i Install the card, boot up NVIDIA Experience, and do a clean install of the newest driver, 350.12. Then I get into a game of League and notice that my FPS has dropped. I kept it capped at 60 FPS on the single card prior to the update (uncapped im usually at 240+ with the single 660). However now i'm between 40-57 FPS, and when I have something running on my 2nd monitor, that regularly drops to ~20-30ish. I removed my 2nd card, reverting back to only 1 of my 660's installed. I get back into a game of League and i'm still at the dropped FPS range.

Is there anybody else using the 350.12 driver that's had the same issue, whether using SLI'd GPUs or a single GPU? If so, especially if using SLI'd GPUs, what is the driver that you are using?

Thanks -DD